1. Field of the Invention
The present invention relates to a ratchet wrench, and more particularly to a ratchet wrench that with adjustable torque.
2. Description of Related Art
Conventional pneumatic tools, such as ratchet wrenches are used to tighten or loosen nuts and bolts, a conventional ratchet wrench in accordance with the prior art comprises a handle, an air-inlet controlling device, a transmitting device and a ratchet head. The air-inlet controlling device is mounted in the handle to control the flow direction of compressed air and communicates with the handle. The transmitting device is mounted in the handle and is connected to the air-inlet device. The ratchet head is connected to the transmitting device to fasten or loosen nuts and bolts by changing flow direction of the compressed air by the air-inlet controlling device and the transmitting device.
Although the conventional ratchet wrench can be used to fasten or loosen the nuts and bolts, the torque force of the conventional ratchet wrench is a fixed value and can not be adjusted according to different kinds of bolts or nuts. Thus, multiple ratchet wrenches with different torque forces are needed to fasten or loosen different kinds of nuts and bolts, but this is inconvenient and costly. In addition, when changing or tightening the nuts and bolts of a vehicle wheel by the conventional ratchet wrench, which has a higher pounds of torque than that for the nuts and bolts, the nuts and bolts are easily stripped due to over-torque.
To overcome the shortcomings, the present invention tends to provide a ratchet wrench to mitigate or obviate the aforementioned problems.